Multiscale Analysis of Drought Teleconnections of West Central India Using Wavelet Coherence

Drought is a natural climate variability that emerged as a result of the prolonged decrease in precipitation. This study used Standardized Precipitation Index (SPI) to evaluate the drought variability over West Central India (WCI) and its association with various climatic oscillations (COs) like Pacific Decadal Oscillation (PDO), El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO) and Indian Ocean Dipole (IOD). The dominant periodicities of the drought index and climatic oscillations were analyzed using Continuous Wavelet Transform (CWT). Partial Wavelet Coherence (PWC) was used to understand the standalone effect of a specific CO on drought, excluding the role of other climatic oscillations. The study investigated the individual and combined influences of the large-scale climatic oscillations at different time scales using Bivariate Wavelet Coherence (BWC) and Multiple Wavelet Coherence (MWC). To identify the most influential climatic driver for the meteorological and hydrological drought of WCI, various multi-factor combinations were considered. The ENSO-PDO combination gave maximum coherence in the case of a two-factor combination for short-term and long-term drought. The maximum coherence value was obtained for the three-factor combination of ENSO-PDO-IOD for all drought conditions. In short, PDO was found to be the most influencing driver in the drought experienced in WCI.